New Subcarrier Allocation for Uplink-OFDMA under Time-Varying Channels

Inter-carrier interference (ICI) and multiuser interference (MUI) occur in an uplink orthogonal frequency division multiple access system if a channel between a mobile user and a base station is rapidly time-varying. To reduce the ICI and MUI, this letter proposes a subcarrier allocation method. The key idea is to allocate a high-speed user´s subcarrier near a low-speed user´s one. Then, a wide Doppler spread of a high-speed user can be spilled over a low-speed user´s subcarrier band with insignificant influence, and the signal-to-interference-plus-noise ratio (SINR) at each high-speed user´s subcarrier can be maximized. This can provide a significant performance improvement of multiuser detection in an uplink-OFDMA.